Contacting element



' Patented Jan. 31,1939

UNl TED; STATES PATENT OFFICE I CONTACTING ELEMENT Franz R. Hansel and Earl I. Larsen, Indianapolis,

Ind., assignors to RR.

Mallory & 00., Inc" Indianapolis, Ind., a corporation of Delaware No Drawing. Application March Serial No. 132.296

(Cl. 200l66) Claims.

in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claims.

While a preferred embodiment of the invention is described herein, it is contemplated that conwithout departing from the vention.

A feature of th present invention is the provision of an electric contact member ofa coma high current carrying cathe contact. a In one of its aspects the invention makes possible the manufactureof contacts having the desirable properties mentioned by casting, such, as die or sand casting. It is found that contacts of the composition contemplated can possess high hardness in the as cast condition. a

The contacts of the present invention also lend themselves to further hardening by heat treatment. v

According to the present invention the con- 40 tacts are composed predominantly of copper with addition of cobalt stances it may be desirable to add small proportions of For example, it has been found that heat treatsilicon, beryllium or phosphorus.

The contacts may be formed of an alloy of the following composition:

Copper rIIIILIII:IIIIII: Balance and cadmium. In some in-' other ingredients to the composition,

Preferred range Per cent Cobalt 1 to5 Cadmium .75 to4 I Copper Balance 5' copper powder.

It has been found of advantage in certain cases where high percentages of cadmium are required 25 used for contactor contacts in the as sintered condition, or a special heat treatment mentioned below can be applied after sintering.

It the alloy is produced by melting and not 40 by sinterlng the contacts, may, if desired, be cast directly into the desired shape.

After casting thecontacts have a hardness of p a high temperature, preferably in the order of 900 C.,,quenching, and then ageing at a lower temperature such as at about 450 C. In most instances it is possible to thermal and electrical conductivities. It is also possible with the composition described to deposit the material on a copper, copper alloy or similar metal plate by means of gas welding or electric arc welding and then beat treating the deposit in the manner'described to providea hardened contact.

whereas copper oxidizes readily. thereby forming a high resistance contact surface, the present in series. The contactors were operated 30 times per minute in this circuit.

After 500,000 operations the pure copper contactors increased in resistance to 1.60 milliohms.

Cas. contacts of the composition:

Per cent Cobalt .L.... 2.4 to 2.5 Cadmium 2.0

, Silicon .6 Copper Balance actually decreased in resistance from about .25 milliohm at the start ofthe test to about .16 milliohm after 500,000 operations.

A cast contact of the composition:

Percent Cobalt 2.5 Cadmium 2.0 Beryllium .4 Copper Balance had a contact resistance of the same operation. This indicates .43 milliohm after The load used I consisted of aircore reactors and resistance grids the improvement in contacthardened whereby their strength and wear re-.

sistance is greatly enhanced. While the-present and advantages, has

invention,

been described herein as carried out in specific embodiments thereof, it-

is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope'of the appended claims.

What is claimed is:

. 1. An electric contacting element composed of about .1 to 10% cobalt, about .1 to 10% cadmium and the balance substantially all copper.

2. An electric contacting element according to claim 1 containing from .01 to 5% of an element selected from the group consisting of silicon, phosphorus and beryllium.

3. An electric contacting element according to claim 1 containing from .01 to 2% of an element selected from the group consisting of silicon, phosphorus and beryllium.

4. An electric contacting element composed of about .1 to 10% cobalt, .1 to 10% cadmium, .01

as to its objects to 2% silicon and the balance substantially all T copper.

5. An electric contacting element comprising a sintered metal product composed of about .1 to 10% cobalt, about .1 to 10% cadmium, .01 to 5% of an element selected from the group consisting of silicon and phosphorus and the halance,sub-' stantially all copper.

. FRANZ R. HENSEI...

EARL I. LARSEN. 

